Heating of bakers&#39; and like ovens



June 4, 1940. 1 E. PO|NTQN ET AL 2,203,180

HEATING OF BAKERS AND LIKE OVENS June 4, 1940. JgE. PolNToN Ix=:r Al.2,203,180 y HEATING 0F BKERS AND LIKE OVENS Filed Feb. l2, 1940 3Sheets-Sheei 5 Patented June 194,0

PATENT OFFICE l L2,203,180 HEATING or Bauens ANDV LIKE ovENs- JohnEdward Pointon and Claude Dumbleton,

Peterborough, England, assignors to Baker Perkins Incorporated, Saginaw,Mich.

Application FebruarylZ, 1940, Serial No. 318,454 In Great BritainDecemberl 16, 1938 1 Claim.

This invention relates to heating means for bakersand klike ovens, moreparticularly of the swinging trayor conveyor type, and has for itsobject the provision of an improvedoven heating modesv of heating as maybe selected by the purchaser or to enable him to change the installationfrom one heat source to another as may be ren dered necessary ordesirable by circumstances. if? f, For example, according to theinvention the oven is provided with `means 4whereby solid fuel rsuch ascoke or coal or pulverised fuel may be used or, if such be notavailable, the oven can be changed over to or substituted by oil or gas3"'1 burner source of heat.

The invention consists in a bakers or like oven wherein the bakingchamber is heated by Perkins steam tubes or like elongatedheat-conductive radiating elements which are heated by combus- 23 tiongases circulated through a substantially closed circuit connected to aheat source.

The invention also consists in a bakers or like oven wherein the bakingchamber is heated byr Perkins or like tubes which project into a ilue orflues forming part of a substantially closed circuit through whichcombustion gases `from a heat source are circulated.

The oven is preferably provided with a chamber forming part of theclosed circuit and open- 30 ing to the exterior of the oven, the openingbeing `available to alternative sources of heat.

The oven may comprise a swinging vtray conveyor having a series ofsuperposed laps between which flues are provided into which the ends of35 the Perkins or like tubes project, the circulating gases ilowingthrough said'flues in parallel.

The flues into which the Perkins tubes project are preferably disposedtransversely of the oven and may be of increasing cross-sectional areain 4G the direction in which the circulating gases flow. The Perkinstubes in each ue may be arranged to project progressively farther intothe flues than the preceding tube in the direction of the gascirculation.

45 In the accompanying drawings which show the invention as applied toan endless pan conveyor oven as disclosed in United States Patent No.1,942,974, issued to Pointon and Beanes January 9, 1934,

50 Figure 1 is a longitudinal sectional elevation;

Figure 2 is a part-sectional plan view;

Figure 3 is a transverse sectional elevation of the oven chamber shownin Figures 1 and 2.

In carrying the invention into effect accord- 55 ing to one convenientmode described by way of `arrangement suitable for affordingalternativev (ci. ion-63) example as applied to a conveyor oven having,for instance, a'number of horizontal laps 5a, 5b, 5c, 5d of the conveyorEwithin the oven chamber,` heating means are disposed midway accordingto the length of the oven chamber and comprise` 5- transverse ues la,1b, 1c, 'Id for the reception' of the ends of sets of Perkins tubes 28extending thereinto from bothv directions. One flue 'la is arrangedbelow the oven conveyor lap 5a, an-v other flue 'Ib is disposed betweenthe laps 5a., 5b 10 ofthe conveyor, a third 'Ic is situated between thelaps 5b and 5c while the fourth flue ld is situated between the lap 5cand the return lap 5d. The transverse flues la, lb, 1c; 'Id areconnected at one side of the oven "with a supply header or 1.5;:

conduit 8 and on the other side with a collecting header or conduit 9.The headers 8 and 9 may be of varying cross-sectional area so that eachtransverse flue will be supplied with an adequate volume of heatinggases.

The supply header 8 at its lower end is connected to a longitudinallyextending supply flue I0 and the upper end of the collecting header 9 isconnected to a return flue I I. This return flue is connected to theinlet of a circulating fan I2, the discharge of which is coupled by adowntake llue I3 with a transverse ue or chamber I 4 which in turn iscoupled to the supply flue I0.

The transverse flue or chamber I4 extends through a side wall I5 of theoven whereby it is 30 connected to the combustion chamber or gratechamber I6 of an exterior furnace Il by which the heating circuit issupplied with combustion gases.

It will be appreciated that with the construction at present concernedthe flues or conduits supplying the heating ilues 1a, 1b, Ic and 'Idextend rearwardly of the oven, the furnace being located at o-ne side ofthe oven while the chamber to which the combustion gases are supplied islocated at the rear of the oven.

The combustion chamber I6 has a ring-shaped or rectangular tuyre gratefor an underfeed Stoker which is preferably as described in our BritishPatent speciccauon No. 504,941, dated May 2, 1939. The arrangement forthe solid fuel furnace may be such that the stoking passage or channelis parallel with the oven or atright angles thereto.

The inlet end of each transverse heating ue 1a, lb, 1c, 'Id may beprovided with ya sliding or hinged damper or llap valve I8 or othermeans so that the proportion of gases 'which ows through each heatingflue may be adjusted in order to regulate the top and bottom heatapplied soi the dovvntake ue I3, the by-pass ue being pro-A vided with-a damper or valve.

Each of the transverse flues 1a, 1b, 1c, 1d may be of increasingcross-sectional area in plan in the direction of flow of the gases .andin order to ensure a uniform quantity of the heat being conveyed by thecirculating gases to the ends of all the Perkins tubes in each conduitthe ends of the tubes may be arranged to project into the transverseflues to an amount increasing progressively or stepwise in the directionof the flow of the gases.

The furnace Il or combustion chamber l6 thereof may be provided withmeans through which burners for pulverised fuel or an oil or gas burnerinstallation may be introduced as a unit by projecting it into thefurnace and sup-porting it therein.

Alternatively the burner devices may be mounted upon a structure mountedadjacent the opening in the wall of the oven so that the ourners projectthrough said opening, it being appreciated that in such case the solidfuel furnace 1s not in position.

Although the invention has been described above with reference toheating flues located midway in the length of an oven, it is to beunderstood that it may equally be applied `to heating ues located at theend of an oven, in which case the Perkins tubes will extend the fulllength of the oven and project into the heating ues at the end Wall.

Again, heating ues may be disposed at intervals along the oven, each seto-f flues being connected to a separate circulating circuit with its ownheat source, or all sets of ilues may be coupled in the one circulatingsystem, suitable dampers being provided to ensure the desired flow ofgases.

The invention may be applied to draw plate or other ovens in whichPerkins or like tubes are used, in each case the heating medium for thePerkins tubes being combustion gases circulated In a heating system forovens wherein the baking chamber is heated by a plurality of elongatedheat-conductive radiating elements, in combina tion, a flue closed offfrom the bakingr chamberand into which said radiating elements extendfor a minor portion of their length, va furnace outside of said bakingchamber, ducts connecting said furnace and flue in a continuous closedcircuit, means for circulating hot products of combustion from saidfurnace through said circuit, and means for venting off .a suitableportion of said gases from the circuit. v

JOHN EDWARD POINTON.

CLAUDE DUMBLETON.

